Die casting is a metal casting process, characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work to an injection mold during the process. Most die castings are made from non-ferrous metals zinc, aluminium, lead and tin-based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used; the casting equipment and the metal dies represent large capital costs and this tends to limit the process to high-volume production. Manufacture of parts using die casting is simple, involving only four main steps, which keeps the incremental cost per item low, it is suited for a large quantity of small- to medium-sized castings, why die casting produces more castings than any other casting process. Die castings are characterized by a good surface finish and dimensional consistency. Die casting equipment was invented in 1838 for the purpose of producing movable type for the printing industry.
The first die casting-related patent was granted in 1849 for a small hand-operated machine for the purpose of mechanized printing type production. In 1885 Otto Mergenthaler invented the Linotype machine, an automated type-casting device which became the prominent type of equipment in the publishing industry; the Soss die-casting machine, manufactured in Brooklyn, NY, was the first machine to be sold in the open market in North America. Other applications grew with die casting facilitating the growth of consumer goods and appliances by making affordable the production of intricate parts in high volumes. In 1966, General Motors released the Acurad process; the main die casting alloys are: zinc, magnesium, copper and tin. Specific die casting alloys include: zinc aluminium; the Aluminum Association standards: AA 380, AA 384, AA 386, AA 390. The following is a summary of the advantages of each alloy: Zinc: the easiest metal to cast. Aluminium: lightweight. Magnesium: the easiest metal to machine. Copper: high hardness.
Silicon tombac: high-strength alloy made of copper and silicon. Used as an alternative for investment cast steel parts. Lead and tin: high density; such alloys are not used in foodservice applications for public health reasons. Type metal, an alloy of lead and antimony is used for casting hand-set type in letterpress printing and hot foil blocking. Traditionally cast in hand jerk molds now predominantly die cast after the industrialisation of the type foundries. Around 1900 the slug casting machines came onto the market and added further automation, with sometimes dozens of casting machines at one newspaper office. Maximum weight limits for aluminium, brass and zinc castings are 70 pounds, 10 lb, 44 lb, 75 lb, respectively; the material used defines the minimum section thickness and minimum draft required for a casting as outlined in the table below. The thickest section can be greater. There are a number of geometric features to be considered when creating a parametric model of a die casting: Draft is the amount of slope or taper given to cores or other parts of the die cavity to allow for easy ejection of the casting from the die.
All die cast surfaces that are parallel to the opening direction of the die require draft for the proper ejection of the casting from the die. Die castings that feature proper draft are easier to remove from the die and result in high-quality surfaces and more precise finished product. Fillet is the curved juncture of two surfaces that would have otherwise met at a sharp corner or edge. Fillets can be added to a die casting to remove undesirable edges and corners. Parting line represents the point; the location of the parting line defines which side of the die is the cover and, the ejector. Bosses are added to die castings to serve as stand-offs and mounting points for parts that will need to be mounted. For maximum integrity and strength of the die casting, bosses must have universal wall thickness. Ribs are added to a die casting to provide added support for designs that require maximum strength without increased wall thickness. Holes and windows require special consideration when die casting because the perimeters of these features will grip to the die steel during solidification.
To counteract this effect, generous draft should be added to window features. There are two basic types of die casting machines: cold-chamber machines; these are rated by. Typical ratings are between 400 and 4,000 st. Hot-chamber die casting known gooseneck machines, rely upon a pool of molten metal to feed the die. At the beginning of the cycle the piston of the machine is retracted, which allows the molten metal to fill the "gooseneck"; the pneumatic- or hyd
Computer-aided design is the use of computers to aid in the creation, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, to create a database for manufacturing. CAD output is in the form of electronic files for print, machining, or other manufacturing operations; the term CADD is used. Its use in designing electronic systems is known as electronic design automation. In mechanical design it is known as mechanical design automation or computer-aided drafting, which includes the process of creating a technical drawing with the use of computer software. CAD software for mechanical design uses either vector-based graphics to depict the objects of traditional drafting, or may produce raster graphics showing the overall appearance of designed objects. However, it involves more than just shapes; as in the manual drafting of technical and engineering drawings, the output of CAD must convey information, such as materials, processes and tolerances, according to application-specific conventions.
CAD may be used to design figures in two-dimensional space. CAD is an important industrial art extensively used in many applications, including automotive and aerospace industries and architectural design and many more. CAD is widely used to produce computer animation for special effects in movies and technical manuals called DCC digital content creation; the modern ubiquity and power of computers means that perfume bottles and shampoo dispensers are designed using techniques unheard of by engineers of the 1960s. Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics, discrete differential geometry; the design of geometric models for object shapes, in particular, is called computer-aided geometric design. Starting around the mid 1960s, with the IBM Drafting System, computer-aided design systems began to provide more capability than just an ability to reproduce manual drafting with electronic drafting, the cost-benefit for companies to switch to CAD became apparent.
The benefits of CAD systems over manual drafting are the capabilities one takes for granted from computer systems today. CAD provided the designer with the ability to perform engineering calculations. During this transition, calculations were still performed either by hand or by those individuals who could run computer programs. CAD was a revolutionary change in the engineering industry, where draftsmen and engineering roles begin to merge, it did not eliminate departments, as much as it merged departments and empowered draftsman and engineers. CAD is an example of the pervasive effect. Current computer-aided design software packages range from 2D vector-based drafting systems to 3D solid and surface modelers. Modern CAD packages can frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle from the inside looking out; some CAD software is capable of dynamic mathematical modeling. CAD technology is used in the design of tools and machinery and in the drafting and design of all types of buildings, from small residential types to the largest commercial and industrial structures.
CAD is used for detailed engineering of 3D models or 2D drawings of physical components, but it is used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components. It can be used to design objects such as jewelry, appliances, etc. Furthermore, many CAD applications now offer advanced rendering and animation capabilities so engineers can better visualize their product designs. 4D BIM is a type of virtual construction engineering simulation incorporating time or schedule related information for project management. CAD has become an important technology within the scope of computer-aided technologies, with benefits such as lower product development costs and a shortened design cycle. CAD enables designers to layout and develop work on screen, print it out and save it for future editing, saving time on their drawings. Computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question.
CAD is one part of the whole digital product development activity within the product lifecycle management processes, as such is used together with other tools, which are either integrated modules or stand-alone products, such as: Computer-aided engineering and finite element analysis Computer-aided manufacturing including instructions to computer numerical control machines Photorealistic rendering and motion simulation. Document management and revision control using product data management. CAD is used for the accurate creation of photo simulations that are required in the preparation of environmental impact reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like, where the proposed facilities are allowed to be built. Pote
Programmable logic controller
A programmable logic controller or programmable controller is an industrial digital computer, ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis. PLCs were first developed in the automobile manufacturing industry to provide flexible and programmable controllers to replace hard-wired relays and sequencers. Since they have been adopted as high-reliability automation controllers suitable for harsh environments. A PLC is an example of a "hard" real-time system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result. PLCs can range from small modular devices with tens of inputs and outputs, in a housing integral with the processor, to large rack-mounted modular devices with a count of thousands of I/O, which are networked to other PLC and SCADA systems.
They can be designed for multiple arrangements of digital and analog I/O, extended temperature ranges, immunity to electrical noise, resistance to vibration and impact. Programs to control machine operation are stored in battery-backed-up or non-volatile memory, it was from the automotive industry in the USA. Before the PLC, control and safety interlock logic for manufacturing automobiles was composed of relays, cam timers, drum sequencers, dedicated closed-loop controllers. Since these could number in the hundreds or thousands, the process for updating such facilities for the yearly model change-over was time consuming and expensive, as electricians needed to individually rewire the relays to change their operational characteristics; when digital computers became available, being general-purpose programmable devices, they were soon applied to control sequential and combinatorial logic in industrial processes. However these early computers required specialist programmers and stringent operating environmental control for temperature and power quality.
To meet these challenges the PLC was developed with several key attributes. It would tolerate the shop-floor environment, it would support discrete input and output in an extensible manner, it would not require years of training to use, it would permit its operation to be monitored. Since many industrial processes have timescales addressed by millisecond response times, modern electronics facilitate building reliable controllers, performance could be traded off for reliability. In 1968 GM Hydramatic issued a request for proposals for an electronic replacement for hard-wired relay systems based on a white paper written by engineer Edward R. Clark; the winning proposal came from Bedford Associates of Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing and servicing this new product: Modicon, which stood for modular digital controller. One of the people who worked on that project was Dick Morley, considered to be the "father" of the PLC.
The Modicon brand was sold in 1977 to Gould Electronics acquired by German Company AEG, by French Schneider Electric, the current owner. One of the first 084 models built is now on display at Schneider Electric's facility in North Andover, Massachusetts, it was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range; the automotive industry is still one of the largest users of PLCs. In a parallel development Odo Josef Struger is sometimes known as the "father of the programmable logic controller" as well, he was involved in the invention of the Allen-Bradley programmable logic controller during 1958 to 1960. Struger is credited with creating the PLC acronym. Allen-Bradley, the manufacturer of the controller, became a major programmable logic controller device manufacturer in the United States during the tenure of Struger. Early PLCs were designed to replace relay logic systems; these PLCs were programmed in "ladder logic", which resembles a schematic diagram of relay logic.
This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver. Modern PLCs can be programmed in a variety of ways, from the relay-derived ladder logic to programming languages such as specially adapted dialects of BASIC and C. Another method is state logic, a high-level programming language designed to program PLCs based on state transition diagrams; the majority of PLC systems today adhere to the IEC 61131/3 control systems programming standard that defines 5 languages: Ladder Diagram, Structured Text, Function Block Diagram, Instruction List and sequential function chart. Many early PLCs did not have accompanying programming terminals that were capable of graphical representation of the logic, so the logic was instead represented as a series of logic expressions in some version of Boolean format, similar to Boolean algebra; as programming terminals evolved, it became more common for ladder logic to be used, for the aforementioned reasons and because it was a familiar format used for electro-mechanical control panels.
Newer formats such as state logic and Function Block (which is similar to the way logic is depicted when using
World War II
World War II known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries; the major participants threw their entire economic and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China, it included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, the only use of nuclear weapons in war. Japan, which aimed to dominate Asia and the Pacific, was at war with China by 1937, though neither side had declared war on the other. World War II is said to have begun on 1 September 1939, with the invasion of Poland by Germany and subsequent declarations of war on Germany by France and the United Kingdom.
From late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Finland and the Baltic states. Following the onset of campaigns in North Africa and East Africa, the fall of France in mid 1940, the war continued between the European Axis powers and the British Empire. War in the Balkans, the aerial Battle of Britain, the Blitz, the long Battle of the Atlantic followed. On 22 June 1941, the European Axis powers launched an invasion of the Soviet Union, opening the largest land theatre of war in history; this Eastern Front trapped most crucially the German Wehrmacht, into a war of attrition. In December 1941, Japan launched a surprise attack on the United States as well as European colonies in the Pacific. Following an immediate U. S. declaration of war against Japan, supported by one from Great Britain, the European Axis powers declared war on the U.
S. in solidarity with their Japanese ally. Rapid Japanese conquests over much of the Western Pacific ensued, perceived by many in Asia as liberation from Western dominance and resulting in the support of several armies from defeated territories; the Axis advance in the Pacific halted in 1942. Key setbacks in 1943, which included a series of German defeats on the Eastern Front, the Allied invasions of Sicily and Italy, Allied victories in the Pacific, cost the Axis its initiative and forced it into strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained its territorial losses and turned toward Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in Central China, South China and Burma, while the Allies crippled the Japanese Navy and captured key Western Pacific islands; the war in Europe concluded with an invasion of Germany by the Western Allies and the Soviet Union, culminating in the capture of Berlin by Soviet troops, the suicide of Adolf Hitler and the German unconditional surrender on 8 May 1945.
Following the Potsdam Declaration by the Allies on 26 July 1945 and the refusal of Japan to surrender under its terms, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August respectively. With an invasion of the Japanese archipelago imminent, the possibility of additional atomic bombings, the Soviet entry into the war against Japan and its invasion of Manchuria, Japan announced its intention to surrender on 15 August 1945, cementing total victory in Asia for the Allies. Tribunals were set up by fiat by the Allies and war crimes trials were conducted in the wake of the war both against the Germans and the Japanese. World War II changed the political social structure of the globe; the United Nations was established to foster international co-operation and prevent future conflicts. The Soviet Union and United States emerged as rival superpowers, setting the stage for the nearly half-century long Cold War. In the wake of European devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia.
Most countries whose industries had been damaged moved towards economic expansion. Political integration in Europe, emerged as an effort to end pre-war enmities and create a common identity; the start of the war in Europe is held to be 1 September 1939, beginning with the German invasion of Poland. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred and the two wars merged in 1941; this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935; the British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the fo
Cutting tool (machining)
In the context of machining, a cutting tool or cutter is any tool, used to remove material from the work piece by means of shear deformation. Cutting may be accomplished by multipoint tools. Single-point tools are used in turning, shaping and similar operations, remove material by means of one cutting edge. Milling and drilling tools are multipoint tools. Grinding tools are multipoint tools; each grain of abrasive functions as a microscopic single-point cutting edge, shears a tiny chip. Cutting tool materials must be harder than the material, to be cut, the tool must be able to withstand the heat generated in the metal-cutting process; the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the workpiece surface. The angle of the cutting face is important, as is the flute width, number of flutes or teeth, margin size. In order to have a long working life, all of the above must be optimized, plus the speeds and feeds at which the tool is run.
Linear cutting tools include tool broaches. Rotary cutting tools include drill bits and counterbores, taps and dies, milling cutters and cold saw blades. Other cutting tools, such as bandsaw blades, hacksaw blades, fly cutters, combine aspects of linear and rotary motion Cutting tools are designed with inserts or replaceable tips. In these, the cutting edge consists of a separate piece of material, either brazed, welded or clamped on to the tool body. Common materials for tips include cemented carbide, polycrystalline diamond, cubic boron nitride. Tools using inserts include milling cutters, tool bits, saw blades; the detailed instruction how to combine the tool assembly out of basic holder and insert can be stored in a tool management solution. The cutting edge of a cutting tool is a important for the performance of the cutting process; the main features of the cutting edge are: form of the cutting edge: waterfall or trumpet. Cutting edge angles form and size of the chamfersThe measurement of the cutting edge is performed using a tactile instrument or an instrument using focus variation.
To quantify a cutting edge the following parameters are used: cutting edge radius for symmetric edges cutting edge ellipse axis for asymmetric edges. Factor K, this is the relation between Sγ and Sα; this can be calculated by the ratio of the two axis of the ellipse. This factor describes the form of the cutting edge. 3 angles: clearance angle, wedge angle, rake angle Δr length and orientation of the bevel One of the most important cutting edge parameters is the K factor. It specify the form of the cutting edge. 1 means a symmetric cutting edge. If the value is smaller the form is called a waterfall. If the value is larger than 1 it is called a trompete. Depending on the cutting material, feed rate and other influence factors a cutting tool with the optimum K factor should be used
Milling cutters are cutting tools used in milling machines or machining centres to perform milling operations. They remove material by their movement within the machine or directly from the cutter's shape. Milling cutters come in many sizes. There is a choice of coatings, as well as rake angle and number of cutting surfaces. Shape: Several standard shapes of milling cutter are used in industry today, which are explained in more detail below. Flutes / teeth: The flutes of the milling bit are the deep helical grooves running up the cutter, while the sharp blade along the edge of the flute is known as the tooth; the tooth cuts the material, chips of this material are pulled up the flute by the rotation of the cutter. There is always one tooth per flute, but some cutters have two teeth per flute; the words flute and tooth are used interchangeably. Milling cutters may have from one with 2, 3 and 4 being most common; the more teeth a cutter has, the more it can remove material. So, a 4-tooth cutter can remove material at twice the rate of a 2-tooth cutter.
Helix angle: The flutes of a milling cutter are always helical. If the flutes were straight, the whole tooth would impact the material at once, causing vibration and reducing accuracy and surface quality. Setting the flutes at an angle allows the tooth to enter the material reducing vibration. Finishing cutters have a higher rake angle to give a better finish. Center cutting: Some milling cutters can drill straight down through the material, while others cannot; this is. However, these cutters can cut downwards at an angle of 45 degrees or so. Roughing or Finishing: Different types of cutter are available for cutting away large amounts of material, leaving a poor surface finish, or removing a smaller amount of material, but leaving a good surface finish. A roughing cutter may have serrated teeth for breaking the chips of material into smaller pieces; these teeth leave a rough surface behind. A finishing cutter may have a large number teeth for removing material carefully. However, the large number of flutes leaves little room for efficient swarf removal, so they are less appropriate for removing large amounts of material.
Coatings: The right tool coatings can have a great influence on the cutting process by increasing cutting speed and tool life, improving the surface finish. Polycrystalline diamond is an exceptionally hard coating used on cutters which must withstand high abrasive wear. A PCD coated tool may last up to 100 times longer than an uncoated tool; however the coating cannot be used at temperatures above 600 degrees C, or on ferrous metals. Tools for machining aluminium are sometimes given a coating of TiAlN. Aluminium is a sticky metal, can weld itself to the teeth of tools, causing them to appear blunt; however it tends not to stick to TiAlN. Shank: The shank is the cylindrical part of the tool, used to hold and locate it in the tool holder. A shank may be round, held by friction, or it may have a Weldon Flat, where a set screw known as a grub screw, makes contact for increased torque without the tool slipping; the diameter may be different from the diameter of the cutting part of the tool, so that it can be held by a standard tool holder.§ End mills are those tools which have cutting teeth at one end, as well as on the sides.
The words end mill are used to refer to flat bottomed cutters, but include rounded cutters and radiused cutters. They are made from high speed steel or cemented carbide, have one or more flutes, they are the most common tool used in a vertical mill. Roughing end mills remove large amounts of material; this kind of end mill utilizes a wavy tooth form cut on the periphery. These wavy teeth form many successive cutting edges producing many small chips, resulting in a rough surface finish, but the swarf takes the form of short thin sections and is more manageable than a thicker more riboon-like section. During cutting, multiple teeth are in simultaneous contact with the workpiece reducing chatter and vibration. Rapid stock removal with heavy milling cuts is sometimes called hogging. Roughing end mills are sometimes known as "rippa" or "ripper" cutters. Ball nose cutters or ball end mills are similar to slot drills, but the end of the cutters are hemispherical, they are ideal for machining 3-dimensional contoured shapes in machining centres, for example in moulds and dies.
They are sometimes called ball mills in shop-floor slang, despite the fact that that term has another meaning. They are used to add a radius between perpendicular faces to reduce stress concentrations. There is a term bull nose cutter, which refers to a cutter having a corner radius, large, although less than the spherical radius of a ball mill; this usage is analogous to the term bull nose center referring to lathe centers with truncated cones. Slab mills are used either by themselves or in gang milling operations on manual horizontal or universal milling machines to machine large broad surfaces quickly, they have been superseded by the use of cemented carbide
A machinist is a person who machines using hand tools and machine tools to create or modify a part, made of metal, plastics, or wood. A traditional machinist is one who can operate, disassemble,reassemble and repair the machine tool as well as build new parts such as gears and shafts using various machine tools such as mills, lathes and planers; some titles reflect further development of machinist skills such as tool and die maker, mold maker and operator. A machinist is one, called on to fix a problem with a part or to create a new one using metal working, plastic, or in some cases, wood. Depending on the company, a machinist can be all of the titles listed above. Under the machinist title are other specialty titles that refer to specific skills that may be more developed to meet the needs of a particular job position, such as fitter, turning hand, mill hand, spline grinder. A group of spline grinders is known as a bunch of mongs. A machinist is called upon when a part needs to be produced from a material by cutting.
Such a part may be needed in the thousands. This could include a machinery part for a production line or anything that can be made from metal or plastic. Producing a part will require several steps and more than one machine tool; each machine tool plays a specific role in cutting away excess material. When large numbers of parts are needed, production planning is required to plan the most logical workflow through a series of machines. Computer numerical controlled machines are a special computer-driven tool that can machine a large variety of shapes, whose use in the workflow depends on the part to be machined. CNC machines are becoming the standard due to their speed, precision and reduced downtime while changing jobs. Production runs consisting of large numbers of parts are more cost effective and referred to as production work in the trade. Conversely, small production runs are sometimes referred to jobbing work. Production engineers use blueprints and engineering drawings to produce detailed specifications of the part its geometry decide on a strategy to make it.
Machine tools are configured by the machinist or toolset and production commences. The machinist works with the quality department to ensure the specifications are maintained in the finished product. Large commercial organizations staff machinists on site in a maintenance mode to ensure continuing operations of the production machinery; the labor cost for this role is lower than costs involved with production shutdowns. Additive machining means 3D printing to create industrial components, prototypes and end-use production parts. Additive machining comes into its own in the manufacturing of small intricate parts, which could not be produced through any other manufacturing process. There are several processes in additive manufacturing which include direct metal deposition, electron beam melting, fused filament fabrication, select laser sintering, variations of each. A machinist is to metal; the most common materials that machinists make parts from are steel, brass and various alloys of these materials.
Other less common materials such as vanadium, lead, or manganese are used as alloying elements for the most common materials. Materials that machinists work with are plastics, rubber and wood products. Machinists work with exotic and refractory metals; the term exotic metals is a general term describing out of the ordinary, rare or special purpose metals. A synonym might be space-age. A list of exotic metals might include, but is not limited to, beryllium, chromium and tungsten, as well as special high-temperature metal alloys like Inconel or Hastelloy; the meaning of the term suggests the need for specialized handling and/or tooling to machine them effectively. While the foregoing were the materials that a machinist would be cutting, the cutters that the machinist uses must be harder and tougher than the materials to be cut; the materials in the cutters a machinist uses are most high speed steel, tungsten carbide, ceramics and diamond. Machinists work to small tolerances within 0.010" or 0.25 mm, sometimes at tolerances as low as 0.0001" for specialty operations.
A machinist deals with all facets of shaping and some aspects of forming metal, although forming is a separate trade. The operations most performed by machinists are milling, drilling and grinding. There are other more specialised operations that a machinist will less be called upon to perform such as honing, keyseating and polishing, to name a few; the tools that a machinist is expected to be proficient with fall into 6 broad categories: Measuring tools: The measuring tools come in several basic varieties: Comparison tools such as adjustable parallels and plain calipers, Direct reading tools such as rules and vernier calipers, Micrometer tools based on screw threads, Indicator tools based on clockwork gear movements, Electronic measuring tools based on transducers. Many of these are digital versions of their mechanical predecessors, as with a digital caliper. Hand tools: The hand tools are the usual complement of tools found in a complete auto mechanic's set except that auto specialty tools would be absent and some outsized tools would be present, such as 1